Groundwater Monitoring And Reporting
CATEGORY OF SERVICE, LOCATION:
RV Park Wastewater Discharge and Groundwater Monitoring, Morgan Hill, California
TYPE OF CLIENT:
Commercial Property Owner, RV Park
BACKGROUND:
The RV Park is located in a rural area of Santa Clara County and has operated since the 1970s. The RV Park provides accommodations for full hookups (water, sewer, and electricity) for approximately 60 RVs, one public restroom and laundry room, and an onsite staff living unit. Wastewater is collected through multiple onsite septic tanks and discharged to three onsite leach fields for disposal. Wastewater discharge from the site is approximately 3,000 gallons per day.
The Water Board is concerned that certain chemical additives typical of RV facilities could impact groundwater resources and require regulation of the RV Park’s wastewater discharge.
The RV Park was enrolled under the Central Coast Water Board General Order No. 2014‑0153‑DWQ, General Waste Discharge Requirements for Discharges To Land By Small Domestic Wastewater Treatment Systems. The Water Board issued a Notice of Applicability and Monitoring and Reporting Program (MRP) that required the RV Park to comply with the following:
RV Park Wastewater Discharge and Groundwater Monitoring, Morgan Hill, California
Installation of a wastewater treatment system
Collection of groundwater samples downgradient of the leach field area
Installation of at least three groundwater monitoring wells downgradient of and around the leach field area
Installation of signage to discourage public use of and disposal of chemicals hazardous to the environment that can be transported from the RV facilities to the Park’s septic tank leach fields
Monthly sampling of the onsite water supply well and septic tanks
Quarterly sampling of three groundwater monitoring wells
Semi-annual reporting of water supply well, septic tank, and groundwater sampling and monitoring results
CLIENT GOALS FOR PROJECT:
The Property Owner seeks cost-effective compliance with the Water Board directives to collect data to demonstrate that wastewater from the RV Park is not degrading groundwater quality and that an onsite wastewater treatment system is not necessary.
PROJECT APPROACH:
Trinity worked with the Water Board for approval to install three groundwater monitoring wells to comply with the MRP and collect groundwater data to demonstrate that wastewater discharge from the RV Park does not impact groundwater or nearby sensitive receptors.
Trinity negotiated with the Water Board that a wastewater treatment system was not needed for the RV Park based on groundwater monitoring data.
Trinity performed septic tank and groundwater monitoring and sampling in accordance with the MRP for a period of one year. After one year, Trinity negotiated with the Water Board to reduce the scope of work required under the MRP which saved the client several thousand dollars.
RESULTS, RESOLUTION, NEXT STEPS:
By negotiating with the Water Board, Trinity saved the client significant costs by demonstrating that an active wastewater treatment system was not necessary for the RV Park.
Trinity further saved the client costs by requesting a reduction to the scope of work and selected laboratory analyses required by the MRP. A revised MRP was issued by the Water Board in which septic tank sampling frequency was reduced from a monthly basis to quarterly basis, groundwater monitoring well sampling was reduced from a quarterly basis to semi-annual basis, and sampling the onsite water supply well was reduced from monthly basis to annual basis.
Trinity will continue to monitor the RV Park’s septic tank system and groundwater quality in accordance with the revised MRP.
Trinity will also continue to seek new ways to improve efficiency and reduce overall costs to the client while maintaining compliance with the Water Board.
CATEGORY OF SERVICE, LOCATION:
Soil, Groundwater and Soil Gas Assessment, Napa, California
TYPE OF CLIENT:
Former Dry Cleaners Property Owner
BACKGROUND:
The former dry cleaner operated for more than 30 years and was previously shown to have impacted groundwater with solvents, but the extent of soils and soil gas impacts were not known. Onsite and offsite utility lines were identified as potential conduits for solvent migration.
CLIENT GOALS FOR PROJECT:
The property owner seeks to redevelop the property, and wants to have the site characterization and remediation completed without adversely affecting redevelopment plans or scheduling.
PROJECT APPROACH:
Trinity developed a work plan for Regional Water Quality Control Board (RWQCB) review, addressing request for a site conceptual model, utilities as conduits, and consideration of multiple point sources at former dry cleaning establishment.
Investigation incorporated soil gas screening, Membrane-Interface Probe, cone penetrometer testing, and shallow and deep well installation utilizing auger drilling. Multiple field events were performed with informal reporting to the RWQCB, to avoid multiple iterations of reporting and workplan preparation.
Completed assessment identifying area of soils impact for potential excavation, and delineating extent of shallow groundwater and soil vapor impacts. Deeper water impacts to be addressed separately.
RESULTS, RESOLUTION, NEXT STEPS:
Field investigation is in progress.
Continued groundwater monitoring and reporting to establish flow direction, gradient and dissolved plume concentration trends.
CATEGORY OF SERVICE, LOCATION:
Soil and Groundwater Site Characterization, Hanford, California
TYPE OF CLIENT:
Major Oil Company
BACKGROUND:
Client had previously disposed refinery liquid wastes and sludge in a surface impoundment at a municipal landfill. The impoundment was subsequently covered with soil, and the landfill was closed. The impoundment area was sold to a private landowner. Previous characterization did not evaluate groundwater, and did not establish extent of impacts laterally or vertically. Regional Water Quality Control Board (RWQCB) requested additional characterization.
CLIENT GOALS FOR PROJECT:
Client goal was to determine cost-effective path to closure for this site.
PROJECT APPROACH:
Trinity developed a workplan for RWQCB review.
Characterization utilized Ultraviolet Optical Screening Tool (UVOST), cone penetrometer testing, soil borings to confirm UVOST data, monitoring well installation
Assessment was completed to RWQCB satisfaction. The assessment included pre-profiling of excavated soils if generated, and provided geotechnical and geochemical data for evaluation of remedial approaches including soil remediation via excavation and disposal and risk assessment modeling.
Risk-assessment approach including fate and transport modeling of chemicals of concern is being utilized to demonstrate that leaving residual waste in-place poses no human health or environmental risk.
RISC4 model is being utilized to evaluate human health and environmental risk based on site-specific data, and potential future impacts to groundwater.
RESULTS, RESOLUTION, NEXT STEPS:
Soil and groundwater impacts were shown to be fairly limited in extent. Combined with the site setting, these results suggested risk assessment would be a cost-effective approach in recommending no further action for site.
Negotiations with RWQCB are in progress.
Continued groundwater monitoring and reporting to establish flow direction, gradient and dissolved plume concentration trends.
CATEGORY OF SERVICE, LOCATION:
Soil and Groundwater Remediation, Sunnyvale, California
TYPE OF CLIENT:
Major Oil Company
BACKGROUND:
Site is a former service station, redeveloped as a strip mall.
Soil and groundwater impacts have been defined.
Residual impacts in shallow water and capillary fringe remain
CAP recommended dual-phase extraction/air sparging (DPE/AS) utilizing three extraction and 30 sparge wells, but at an estimated cost of $750,000 to implement to achieve closure
CLIENT GOALS FOR PROJECT:
Cost-effective remediation, maintaining regulatory compliance.
PROJECT APPROACH:
Conducted 11-day DPE/AS pilot test to gain design parameters for SVE/AS system
Evaluate additional alternatives including risk assessment to achieve closure.
RESULTS, RESOLUTION, NEXT STEPS:
DPE/AS shown to be an effective remedial option based on pilot test results. However, full-scale implementation may not be cost-effective, because most residual mass is in fine-grained soils.
Continued groundwater monitoring is underway to evaluate the longer-term effect of the DPE/AS test.
Site may be suitable for risk-based closure in view of low residual concentrations and lack of nearby receptors.
CATEGORY OF SERVICE, LOCATION:
Groundwater Monitoring Program Reduction, Santa Cruz, California
TYPE OF CLIENT:
Former Retail Service Station Owner/Operator
BACKGROUND:
The former station is currently an automobile repair business and was utilized as a gasoline station from 1950 until approximately 1987. The waste oil tank and three underground storage tanks (USTs) and product islands were removed in 1992. No USTs remain at the site. A total of 29 groundwater monitoring wells define a commingled petroleum hydrocarbon plume which is approximately 800 feet long and 360 feet wide in an area of mixed residential, retail and commercial property uses. The Central Coast Regional Water Quality Control Board (CCRWQCB) issued a Monitoring and Reporting Plan (MRP) for the site in August 2006.
CLIENT GOALS FOR PROJECT:
Reduce the MRP requirements for the 29 wells to reduce costs.
PROJECT APPROACH:
Prepare a detailed proposal for groundwater monitoring reduction including discussions on background and local land use, summary of well installations and plume definition, summary of site conditions, review of site Constituents of Concern (COCs) and propose a revised MRP.
RESULTS, RESOLUTION, NEXT STEPS:
Sampling frequency and laboratory analyte reductions were proposed and accepted. Inter-plume and redundant data collection wells were placed on standby. A revised and more cost effective MRP was prepared for the site by the CCRWQCB.
As a result of the monitoring reduction, costs for monitoring were reduced by approximately 50%. Further monitoring reductions have reduced costs by an additional 10%.
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